My vents will still blow hot or cold air, but only when I'm driving fast. So I'm assuming its the fan that doesn't work. But what other problems could it be and what would the estimated repair cost be?
Fan Problem on 1994 Nissan Maxima
Could be the fan, fan resistor or another part of the heater motor control system. Look at the RepairPrice Estimator for prices on replacing the blower motor and the blower motor resistor.